Device for fixing a pulley

ABSTRACT

Device ( 10 ) for fixing a pulley ( 40 ) comprising a rotating pin ( 12 ) on the outer surface of which the pulley ( 40 ) may be fixed, said rotating pin ( 12 ) having at least one locking element ( 50 ) movable between a first locking position where it retains the pulley ( 40 ) and a second releasing position where it does not retain it, the at least one locking element ( 50 ) being coupled with at least one element ( 60 ) which can be operated by the user so that the displacement of said at least one element ( 60 ) which can be operated by the user causes the displacement of said at least one locking element ( 50 ) between said first and second position.

The invention relates to a device for fixing a pulley, intended in particular for gearmotors used in roller blinds.

In very many applications it is required to employ pulleys in order to transmit a rotating movement, raise loads, vary the direction of a cable, etc.

Normally the pulleys (or generally a rotating wheel) are fixed to the pin on which they rotate either permanently or otherwise via fixing means which range from split pins to bolt-type fastening systems. Not infrequently the pulley must be removed from the pin by means of a very quick and simple operation, for example so as to replace it with a different pulley. An example of this arises in the sector of tubular gearmotors to which reference will now be made by way of example.

Tubular gearmotors for moving and/or automating roller blinds, such as shutters, blinds and curtains, at present are designed in such a way that they may be inserted inside a winding drum on which the said shutter is wound (and unwound). They comprise principally an electric motor, a speed reducer and a capacitor, which are housed inside a tubular body. Two pulleys for transmission of the rotating movement from the gearmotor to the winding drum are provided at the ends of the metallic tubular body.

The transmission pulleys have a grooved external profile which matches the internal form of the winding drum. The first pulley is mounted on an output pin of the gearmotor, while the second pulley is mounted on the end-of-travel mechanism. The invention relates to the first pulley.

Usually this pulley is fixed to the rotating pin either with permanent fixing means (screws, washers, etc.) or by means of a tongue arranged on the rotating pin. The tongue engages inside a corresponding seat of the pulley once the latter has been inserted on the pinion. The pulley also has, formed in it, a groove inside which a screwdriver can be inserted in order to lower the tongue and extract the pulley from the pinion.

This solution has the disadvantage that the pulley replacement operation requires precisely the insertion of a screwdriver, for which the installation operator must use one hand, while with the other hand the pulley must be removed.

If one considers that very often replacement is performed once the gearmotor has been installed and therefore in a position which is not easily accessible (for example inside the recess of a wall reached by means of a ladder), it is easy to appreciate the awkward nature of this operation and the danger of not being able to hold on with at least one hand.

The main object of the invention is to provide a fixing device for a pulley which can be easily released.

This object is achieved with a device for fixing a pulley comprising a rotating pin on the outer surface of which the pulley may be fixed, said rotating pin having at least one locking element movable between a first locking position were the pulley is retained and a second releasing position where it is not retained, characterized in that said at least one locking element is coupled with at least one element which can be operated by a user, the displacement of said at least one element which can be operated by the user causing the displacement of said at least one locking element between said first and second position.

The advantages and characteristic features of the present invention will emerge more clearly from the following description of an embodiment to be regarded solely as being an example The description refers to the accompanying drawing in which:

FIG. 1 shows a partial three-dimensional view of a gearmotor which uses a device for fixing a pulley according to the invention;

FIG. 2 shows a front view of a pulley of the fixing device according to FIG. 1;

FIG. 3 shows a cross-sectional view of the fixing device according to FIG. 1 along the cross-sectional plane I-I of FIG. 1.

In the figures a fixing device 10 according to the invention is mounted on a gearmotor 11. The device 10 comprises, at one end, a rotating pin 12 with grooves 17 having a cylindrical coaxial cavity 14 which opens outwards at a free end of the rotating pin 12. Said cavity 14 has a side surface 16 and a bottom surface 18.

The rotating pin 12 is coupled to a motor via a reducer (not shown) of the gearmotor 11 and has the function of transferring the rotational movement thereof. A pulley 40 (see FIG. 1) has an outer toothing 42 shaped so as to mesh with the inner part of the winding drum of the roller blind when operated (not shown) and an inner toothing 44 formed in a central through-hole 45 and corresponding to the groove 17 of the rotating pin 12 on which it is to be mounted. The toothing 44 comprises, in diametrically opposite positions, two longitudinal grooves 46 a,b which extend from one edge of the toothing 44 over about half the depth of the latter.

The cavity 14 of the rotating pin has, on the side surface 16, two diametrically opposite holes 20, 22 with inner lying edges 21 a, 21 b, while in the centre of the bottom surface 18 it has a bush 24 formed raised from the bottom surface 18.

A locking element 50 (see FIG. 1) has a symmetrical form (so that suffixes “a” and “b” will be used for identical parts) and comprises two locking teeth 52 a,b situated at one end of two diverging arms 54 a,b which are curved at the other end so as to form a kind of “V”. A pin 56 and a nail-shaped body 58 with a head 60 extend from the centre of the “V”. The locking teeth 52 a,b are connected to the arms 54 a,b by means of two inclined segments 62 a,b.

The locking element 50 is inserted inside the cavity 14, as can be seen in FIG. 3. In particular it can be noted that the pin 56 is engaged inside the bush 24, but has the possibility of performing a further travel movement inside it, and the head 60 closes the cavity 14, being able, however, to slide along its side surface 16. Moreover, the locking teeth 52 a,b protrude from the holes 20,22 and the inclined segments 62 a,b bear against the edges 21 a,b of the holes 20, 22. Obviously, in order to obtain this configuration, the dimensions of the various parts which form the locking element 50 must be chosen so as to correspond to the dimensions of the cavity 14, the holes 20,22 and the bush 24.

The operating principle of the locking element 50 is now described. Once it has been inserted as described inside the cavity 14, the pulley 40 (see FIG. 3) is mounted on the rotating pin 12 so as to cause engagement of its inner toothing 44 with the grooves 17 of the rotating pin 12 and produce alignment of the holes 20, 22 with the grooves 46 a,b, which remain directed towards the head 60. Then, by pushing the pulley 40 onto the rotating pin 12, initially the locking teeth 52 a,b move downwards with respect to the groove 17 inside the holes 20, 33 since they are pushed by the toothing 44 of the pulley 40, but move back upwards, owing to the elasticity of the arms 54 a,b, when they are reached by the two longitudinal grooves 46 a,b of the pulley 40, and are arranged inside said two longitudinal groves 46 a,b. It can be seen from FIG. 3 that the pulley 40 is locked on the rotating pin 12 by the teeth 52 a,b which bear against one wall of the grooves 46 a,b. In order to release the pulley 40, the head 60 is pushed inside the cavity 14, in a direction F shown in FIG. 3. This causes the pin 56 to move inside the bush 24 and pushes the arms 54 a,b towards the bottom surface 18 of the cavity 14. Therefore, the inclined segments 62 a,b slide on the edges 21 a,b of the holes 20, 22 with the effect of retracting the teeth 52 a,b inside the cavity 14. Now the pulley 40 is no longer retained and may be removed from the rotating pin 12. The elasticity of the arms 54 a,b produces moreover a “spring” effect in the locking element 50, since, once the head 60—which acts like a pushbutton—is released, it returns into the initial position, bringing the teeth 52 a,b into the locked position.

Obviously, the invention may be subject to numerous variations. For example, it is possible to keep the form of the arms 54 a,b in the locking element 50, to eliminate the pin 58 and the body 58 and to form an extension for each of the two arms 54 a,b which extends outside the cavity 14, instead of the body 58. By moving these two extensions towards it each other, retraction of the teeth 52 a,b is obtained. Transmission mechanisms, such as gearwheels or lever systems, may be used between the locking teeth 52 a,b and the head 60 (or a generic element which can be operated by a user).

The invention may advantageously be used in many applications, such as, for example, toys (in order to fix/detach wheels or components in models or in the construction sector). All these variations are included within the scope of protection of the following claims. 

1. Device (10) for fixing a pulley (40) comprising a rotating pin (12) on the outer surface of which the pulley (40) may be fixed, said rotating pin (12) having at least one locking element (50) movable between a first locking position where it retains the pulley (40) and a second releasing position where it does not retain it, characterized in that said at least one locking element (50) is coupled with at least one element (60) which can be operated by the user, the displacement of said at least one element (60) which can be operated by the user causing the displacement of said at least one locking element (50) between said first and second position.
 2. Device (10) according to claim 1, wherein said at least one locking element (50) in the first position protrudes from a corresponding hole (20, 22), with an edge (21 a,b), present on the outer surface of the rotating pin (12) and in the second position is retracted inside said hole (20, 22).
 3. Device (10) according to claim 1, wherein said rotating pin (12) has a coaxial cavity (14) with a bottom surface (18), which cavity (14) opens outwards at a free end of the rotating pin (12) and inside which said at least one locking element (50) is housed.
 4. Device (10) according to claim 3, wherein said element (60) which can be operated by the user is slidable along said cavity (14).
 5. Device (10) according to claim 1, wherein said element (60) which can be operated by a user is an extension of said at least one locking element (50).
 6. Device (10) according to claim 5, wherein said locking element (50) comprises two locking teeth (52 a,b) situated at one end of two arms (54 a,b) to which they are connected by means of two inclined segments (62 a,b), said two arms (54 a,b) being curved at the other end so as to form a “V”, from the centre of which a pin (56) and a nail-shaped body (58) with a head (60) extend in opposite directions, said two locking teeth (52 a,b) being able to protrude from the outer surface of the rotating pin (12) through two holes (20, 22).
 7. Device (10) according to claim 6, wherein the bottom surface (18) of said cavity (14) has a bush (24) inside which the pin (56) is engaged such that it has the possibility of performing a travel movement inside the latter, and in which the head (60) closes the cavity (14), being able to slide inside it, while the locking teeth (52 a,b) protrude from said holes (20, 22) and the inclined segments (62 a,b) bear against the edges (21 a,b) of said holes (20,22).
 8. Device (10) according to claim 1, wherein elastic means keep said at least one locking element (50) in the first position.
 9. Gearmotor (11) for roller blinds comprising the fixing device (10) according to claim
 1. 